Genetic and phenotypic parameter estimates for growth, yield and meat quality traits in lamb

摘要

The Meat and Wool New Zealand Central Progeny Test has evaluated 143 sires from terminal and dual purpose breeds for meat yield and growth. Meat quality traits, including pH, fat and meat colour (CIE L*, CIE a*, CIE b*) have also been measured. This paper determines genetic variation in these quality traits and their correlations with growth and meat yield. Progeny were drafted for slaughter at a threshold live weight of 34 kg at weaning and 36 kg for subsequent slaughters. Fat colour, eye muscle meat colour and meat pH were measured 24 hours post-slaughter, with meat colour measured after a 30 minute bloom. Heritabilities and genetic correlations between traits were calculated from the measurements. Data were analysed with a linear mixed model in ASReml. Results showed significant variation among sires for meat quality. Heritabilities were moderate for most meat quality traits: fat colour (CIE b* 0.42), initial meat colour (CIE L* 0.29, CIE a* 0.19) and pH (0.12). Relationships between meat quality and yield/growth showed that meat CIE L* had a positive genetic correlation with weaning weight (0.42). Simulated index selection for growth rate and meat yield predicted a small increase in meat lightness and decline in fat yellowness (0.231 and -0.227 units per generation and unit selection intensity, respectively).